Apparatus for testing and timing photographic exposures



M. L. ASH, JR 2,268,436

IMING PHOTOGRAPHIC EXPOSURES Dec. 30, 1941 APPARATUS FOR TESTING AND TFiled Aug. 17, 1938 2 Sheets-Sheet l f HUUNNIIH :IHMM WNMUMHMMMINIMHH oDec 30, 1941. M. L. ASH, ,JR

APPARATUS FOR TESTING AND 'I' 2,268,436 IMING PHOTOGRAPHIC ExPosUREs 2Sheets-Sheet 2 Filed Aug. 17, 1938 NNN @E EEDEDUEDEEEEEEEED @wwwMw.00N..oewooumosol-Nnoocncwooo ooo.

Inventor Mawr/cel; f7;

Patented Dec. 30, 1941 APPARATUS FOR TESTING AND'TIMING PHOTOGRAPHICEXPOSURES Maurice L. Ash, Jr., Detroit, Mich. 1

Application August 17, 1938, Serial No. 225,388

(Cl. {l- 19) 1 claim.

This invention relates, in general, to photographic reproductions "and,in particular, to an improved method of and apparatus for determiningthe proper duration of time required for obtainingproperly'ciear anddetailed exposures and employing this determination for controlling 4theattainment of the reproductions.

The main object of this invention is to providean improved method of andapparatus for determining the duration of time of exposure vnecessaryfor the properly detailed reproduction of images iromnegatives, and totime the process o'f said reproduction in accordance therewith.

Another object of the invention is to provide the period of time duringwhich printing paper will become exposed to the desired extent, bymoving ya shutter `and ar test strip of said paper relatively to eachother in the path of light which is passing through the negative, andobtainingon said strip an infinite number oi innitesimal stages ofexposure, each stage representing an exposure of diierent duration fromthose of adjacent stages, .choosing the desired stage, and using thetime therefor as a standard for the length of exposure of said printingpaper in the path'of said light.v

Another object is to provide an improved methodof and apparatus fordetermining the lengthof time necessary for detailed reproductions ofimages from film negatives and for employing this same length of time asa standard of time for the exposure of printing paper, by progressivelycoveringa 'test strip of said printing paper'in the path of projectedlight with a shutterl to' expose said test strip between points of toolittle and too great exposures, selecting a pointon said exposed test.strip at which proper exposure appears, and then exposing said printingpaper in the path of said light for the same length of time that saidselected point on said test strip was exposed.

Another object .ofthe invention is to provide an improved testing andtiming apparatus for use inphotographic reproductions 'which permit atest strip zof printing paper to be moved relatively with respect to ashutter in the path of projectedlight which ispassing through a negativebearingthe images to be reproduced, the teststrip becoming therebyexposed between points oiv relative exposure and permitting theselection therefrom of a position of properly detailed Aexposure?. lyingtherebetween, said apparatus being provided. with means for recordingthe time required for the selected exposure so that said time can beused as a standard for the proper exposure ofsaid 'printing paper.

Still anotherobject of the invention is to provide an improved testingand timing devicev employed in the art of making reproductions 'ofimages Vfrom nlm negatives which recordson a test strip oi printingpaper the position of the best available exposure. and which permits theuse of' this record for establishing the time for exposure of saidprinting paper.

Other objects and advantages of the invention will become readilyapparent from a reference to the following specication taken inconjunction with-the accompanyinfr drawings of which there re two (2)sheets and wherein:

Figure l is a plan View of the novel testing` and timing apparatusemployed in the novel method, same being shown partly in section andpartly broken away to show details of the construction thereof;

Fig. 2 is a part elevational and part sectional View taken along thelines .-2 in Fig. l;

Fig. 3 is a sectionalr View taken along the lines 3 3 in Fig. l;

Fig. 4 is an enlarged plan view of the combination opaque-translucentshutter employed in the novel method;

Fig. 5 is a plan view of an exposed test strip showing the normal rangeof exposures and with the subjects of enlargement variably exposedthereon;

Fig. 6 is a plan view ofan exposed test strip showingthe upper range ofexposures;

Fig. 7 is a perspective View, shown diagrammatically, of the enlargingapparatus with the testing and timing apparatus in place with respectthereto; and

Fig. 8 is aview similar to Fig. 'l but showing the stage of theenlarging process subsequent to the determination of the desired time ofexposure.

In the figures there is shown a hollow, boxlike casing, generallyindicated at l0, in which is housed and supported the apparatus foraccurately determining and controlling the correct periods of timenecessary for clear and detailed exposures in photographicreproductions. The top wall of casing l0 is provided with an L- shapedopening l2 running longitudinally thereof and with a pair oflongitudinal slots I4 and I6, slots I4 and I6 being spaced from eachother and parallel to opening l2. Formed on the underside of the top ofthe casing I, adjacent each end and on either side of opening l2, is aboss I8 internally bored to provide a bearing thereat having atransverse axis. Also on the underside of the top of casing IU, adjacenteach end of slot I4 and in alignment therewith, there is formed a boss20 internally bored to provide a bearing thereat having a longitudinalaxis. In axial alignment with two of the end bearings I8 there isprovided a bearing having a transverse axis formed in an internallybored boss 22 which extends from and is supported by the underside ofthe top of casing Il! adjacent one end of the slotv IS.

J ournaled in one group of axially aligned bearings I8 adjacent one endof opening I2 is a transverse shaft 26, while journaled inthe othergroup of axially aligned bearings I8 adjacent the opposite end ofopening I2 is another transverse shaft 28, shaft 28 being also journaledin bearing 22 adjacent one end of slot I6. to each of the shafts 26 and28 between the respective set of bearings I8 for each thereof is atoothed drum 2S, each of said drums being provided at its periphery withtwo sets of axially and circumferentially spaced teeth 30, the axes ofdrums 28 being parallel and in substantially the same horizontal plane.The number of teeth 30 on each drum 29, their pitch and their spacing,are factors which are readily determined, as will appear subsequently.

At or near the endV of slot I6 which is remote from the bearing 22,between slots I4 and I6, there is provided a spring arbor 'comprising apair of horizontally spaced vertical plates 34 (see Figs. 1 and 2) whichextend for a substantial distance in longitudinal parallelism within andwith respect to casing I8.v Plates 34 are secured in any suitable mannerto the casing I8 for being supported thereby, such as by being formedwith end flanges 36 extending laterally and being secured thereat to anend wall of said casing by means of bolts, screws or rivets 38.

Plates 34 are provided with a pair of aligned openings in which isjournaled a transverse shaft 48, said openings being so positioned as topermit shafts 28 and 40 to be substantially parallel and occupysubstantially the same horizontal plane. Intermediate the ends of shaft48 there is mounted for rotation therewith a sprocket wheel 42 (see Fig.2) having a hub 44 (see Fig, 1) adapted for securing said wheel to saidshaft, hub 44 and a nut 46 on one end of shaft 48 serving to preventshaft 4I] from accidental axial movement. The opposite end of shaft 40is optionally provided with a hand nut 48, or other means, for enablingthe ready manual turning ofv shaft 48. Wheel 42 is disposed immediatelybetween one of the plates 34 and one of the longitudinal walls of thecasing I8 and is in longitudinal and circumferential alignment withanother sprocket wheel 58 (see Figs. 2 and 3) mounted on the shaft 28adjacent the bearing 22, wheels 42 and 58 being positioned for occupyingthe same vertical plane and having the same pitch, said wheels being indriving and driven communication with each other, re-

spectively, by means of an endless chain 52.

Between the plates 34 of the spring arbor, on shaft 48, Vthere is freelymounted a relatively large driving gear 54. In mesh with gear 54, xedlyon a shaft 56 which is supported between the plates 34 and journaledtherein in spaced relation Vto shaft 48, is a relatively small drivengear 58. Laterally of gear 58 on shaft 56, and xed'for rotation withshaft 56 and gear 58, is another of the gears 60 of the escapementmechanism at present being described. In parallelism with shafts 48 and56, and supported between the plates 34 and journaled therein,` isanother shaft 82`to and about which is pivoted the ordinary pawl 64 ofsaid escapement mechanism. The lower end of pawl 64, as usual, isbifurcated, its bifurcations being disposed between non-successive'spaced teeth on the gear 60 on shaft 56, one of said bifurcations, asshown in Fig. 2, being in engagement with the leading face of one ofsaid teeth on gear 68 and the other of said bifurcations being, asusual, slight- Keyed p ly out of engagement with the following face ofthe third tooth on gear ahead of said other tooth thereon. The upper endof pawl 64 is splined, as at 66, for receiving an adjustable nut 68thereon, nut 68 being adapted for decreasing or increasing the distancebetween it and the pivot 62 of pawl 64, an increase thereof lengtheningthe time for each oscillation of pawl 64 and a decrease thereofnaturally shortening said time.

Fixedly mounted on the shaft 48 immediately adjacent the driving gear 54is an annular ratchet 'I8 having a plurality of spaced, axially directeddetents 'I2 (see Fig. l) which are engageable with slotted openings (notshown) in the adjacent face of the gear 54. During movement of the shaft40 and rachet 'I0 in counterclockwise direction, detents 'I2 are adaptedfor sliding over said openings in gear 54 While the pawl 64 and gear 60.are being locked together against movement, thereby causing gears 54 and58 also to be locked together against movement; During movement of theshaft 48 and ratchet 'I0 in a clockwise direction, however, detents 12are adapted for locking engagement with said openings in gear 54 todrive said gear, gear 68 and pawl 64 at the same time operating in themanner characteristic of the ordinary escapement mechanism.

Intermediate the shaft 48 and the end wall of casing I0 which supportsthe plates 34 is a stationary shaft 'I4 which is supported between theplates 34 and about which shaft is fixedly supported an end of a spiralspring 16, said spring being coiled upon itself about the shaft 48 andhaving its opposite end xedly mounted to said shaft 48. When the shaft48 is turned in a counter-clockwise direction by such means as the handnut 48, and the pawl 64 is caused to lock the gear 68 against movement,which locking of gear 88 simultaneously causes the locking together ofgears 58 and 54 against movement, the spring 'I6 becomes compressed uponitself, or wound up. Then, when the operatcrs hand is released from nut48, the spring 'I6 unwinds itself with a speed which is controlled bythe escapement mechanism, the gear being released from the pawl 64 andthe speed of rotation of gear 88 thereafter being controlled by theoscillations of pawl 64 in the ordinary manner, gear 54 having beenreleased from the detents 'I2 on the ratchet 'I0 when counter-clockwisemovement of shaft 48 ceases and the spring 'I6 is allowed to unwind anddriving gears 58 and 80 in accordance therewith. It should be notedthat, whether the shaft 4D is turned clockwise or counter-clockwise, thesprocket wheel 42 thereon, through the chain drive 52 and the sprocketwheel 5I) on shaft 28, drives said shaft 28 in accordance with saidturning of shaft 48.

As isA necessary in any type of escapement mechanism there must beprovided some means whereby the pawl 64 is prevented from oscillatingduring the spring winding operation since, otherwise, the gear 6U wouldbe free to rotate during said winding operation. Therefore, between andto the plates 34 of the spring arbor and escapement mechanism there ismounted a shaft 'I8 on which is pivotally supported a lever 88. Thepivoted end of lever 88 is provided'with oppositely directed lugs 82 and84, lug 82 being directed toward the pawl 64 and engageable therewithfor locking same against oscillation when the lever 80 is moved slightlyclockwise about its pivot, and lug 84 being directed in an oppositedirection from lug 82 and having secured thereto one end of a spring 86,the other end of spring 8S being anchored to one of the stationaryplates 34, and spring 86 normally constraining lug 82 out of engagementwith pawl 64. The free end of lever 80 extends upwardly through thecasing |0 between the slots |4 and I6 therein. Intermediate the lugs 82and 84 and the free end of lever 80 there is disposed an arm 88, one endof said arm hooking over the lever 80 and the other end of said armbeing rigidly attached to the underside of a longitudinal bar 90 whichis slidably mounted in the bearings of the bosses 20 and underlies theslot I4. Bar 90 is limited in movement in one direction by a rigid stop92 and in the opposite direction by a resilient stop 94. Mounted on thebar 00 intermediate its ends is a boss 96 which has an internallythreaded portion 98 extending upwardly through the slot I4 thereat andin which is disposed a set screw |00 which is adapted for locking boss96 to bar 90 or permitting its slidability therealong, as desired.Portion 98 of boss 96 is provided with a pointer |02 which adjacentlyoverlies the top of the casing I0 and points in a general directiontoward the opening I2 therein. It will be noted that movement of bar 90toward the right in Figs. 1 and 2 against the force of the resilientstop 04 causes the arm 88 to bring the lug 82 of lever 80 intoengagement with paWl 64 to prevent oscillation of the latter.

The normal position of the mechanism, however, is that shown in Fig. 2.

The means for winding the spiral spring I6 of the escapement mechanismhas already been indicated at 48, the manually operated hand nut.However, the hand nut 48 can either be complemented with or replaced bya boss |04 which is formed to slide in and along the slot |6 and haveits lower portion rigidly attached to one of the links of the chaindrive 52. Therefore, as shown in Figs. 1 and 2, if the boss |04 is firstpermitted to move along the slot I6 with the chain 52 toward the rightduring unwinding of the spiral spring 18, it is possible to re-wind thespring thereafter by merely forcing by hand the boss |04 back into theposition thereof shown in Figs. 1 and 2.

Disposed around the drums 29 is an endless shutter, generally indicatedat |06, having marginal perforations engageable with the teeth 30 onsaid drums for being driven thereby. Shutter |06 is preferably ofCelluloid material, but can be of any other suitable material which willserve the purpose thereof. Shutter |06 is composed of an opaque section|08, a translucent section I I0 and a marginal opaque section ||2extending for a selected distance from section |08 along sectionSupported by the casing |0 slightly above the upper level of the shutter|06 is an L-shaped plate ||4, the plane of plate ||4 being disposed inparallelism with the upper plane of shutter |06 and Adefining along itslongitudinal length a portion of the opening I2 and having itstransverse length overlying said opening (see Fig. l). Along saidlongitudinal length of said plate there is stenciled or Otherwiseperforated a series of equally spaced indicia, numerals being shown forthe purpose of illustration, and longitudinally along said transverselength of said plate there is stenciled another series of equally spacedindicia, letters being shown for the purpose of illustration. Eachletter employed is longitudinally positioned so as to be aligned withone of the numerals employed. At a distance to the left of Gil the firstnumeral in the succession, which is equal to the distance between anytwo adjacent numerals, there is indicated on the top of the casing I0 anormal starting point for the shutter |08, such as 0, and from said 0letters similar to the aforesaid letters are set off on the top of saidcasing from right to left in the same succession and with the samespacing as aforementioned.

To the shutter |06, at the break between the sections |08 and l0, thereis cemented or otherwise secured an arm ||S which extends transverselyof said shutter and forwardly thereof to a point at least up to thelongitudinal centerline of the slot I4. This extension of arm I I6permits engagement between the said arm and the neck portion B8 of theboss 28 when the former reaches the transverse centerline of the latterduring the travel of the former toward the right.

Underneath the movable shutter |06 and the numeric and lettered indiciaon stationary plate H4, there is stationarily supported a test strip ||8of the printing paper that is to be used in the final enlarging process.With strip ||8 so in place the casing I0 is placed in the enlargingmachine, generally and diagrammatically illustrated at |20, on the easel|22 thereof, the sensitive side of said strip facing the lens |24 of themachine |20. Between the lens |24 and the usual lamp housing |28, in thelatter of which is disposed the usually energized lamp (not shown),there is disposed a negative |28 from which the image thereon is to bereproduced on the test strip H3, and later on the printing paper |30which is the source of said test strip. After the casing I0 has been soplaced on the easel |22, the lamp in housing |20 is illuminated in theusual manner, the escapement mechanism in casing |0 being simultaneouslyset into motion, it being presumed that the test strip ||8 is entirelycovered by the translucent section of the shutter |0u` at this time. Ifthe arm IIS is in the position shown in Figs. 1 and 2 when the casing I0is positioned as in Fig. 7, the test strip ||8 will be exposed as shownin Fig. 6, the portion thereof at the left being under-exposed since itis that portion which is first covered by the opaque section |08 of theshutter |06, the portion at the right being over-exposed since it isthat portion which is later covered by said opaque section, and theintermediate portion blending with said other portions. The position ofthe arm H8 in Figs. 1 and 2 is employed when the highest range ofexposures is desired, such as when the factors determining the properlength of time of exposure demand it, these factors including thedensity of the lm |28, the distance between the lens |24 and easel |22,the sensitivity of the printing paper |30, and the lamp intensity. It isclear that the skillful operator, when he has a test strip such as isshown in Fig. 6 before him, can readily select that portion thereonrepresentative of the clearest and most detailed exposure. The teststrip shown in Fig. 6 is the result of having begun the motion of theescapement mechanism after the arm IIS had been placed in the positionshown in Figs. l and 2 and the casing I0 had been placed in the positionshown in 7, the test strip therefore being wholly covered by thetranslucent section |10 of the shutter |06 for the length of time theescapement mechanism required for bringing the arm H5 directly over theindicium 0 provided on the top of casing I0 (as distinguished from theindicium 0 provided on the plate I4), and being thereafter covered in agradual and progressive manner by the opaque section |08 of the shutter|06, the opaque section ||2 o1 the` shutter |06 at the same timegradually and progressively covering the lettered indicia on plate H4while the opaque section |08 of the shutter is covering both thenumbered indicia on plate H4 and the lettered indicia on the top ofcasing I0. The result is clearly represented in Fig. 6.

However, since normal factors which vary the time of exposure usuallyprevail, the arm H6 which is secured to the shutter |06 between itsopaque and translucent sections |08 and ||0 is placed at the indicium onthe top of casing I0. The casing with its test strip inserted therein`in its proper position is then placed on the easel |22 and the lamp andescapement mechanism are simultaneously put into operation. Theescapement mechanism gradually draws the shutter |06 across the teststrip, the portion of said strip underlying the translucent section I|0of said shutter being fully exposed but gradually covered by the opaquesection |08 of said shutter, and the numbered indicia on the plate H4being at the same time gradually covered by said opaque section, thelettered indicia on both the plate H4 andthe top of casing I0 havingbeen originally covered by the act of moving the arm IIB to the normalposition above described, The result is clearly indicated in Fig. 5.

With the test strip of Fig. before the operator, he can readily selectthe position thereon which represents the iinal exposure desired. Thisposition having been selected, the pointer |02 is moved thereto alongthe slot I4 on bar 90 and xed thereat by means of the set screw |00. Thecasing l0 is then set within the Vicinity of the enlarging machine, theprinting paper |30 is placed in the usual manner on the easel |22, andthe enlarging lamp is illuminated while, at the same time, theescapement mechanism is set in motion (the arm H6, of course, being atthe indicium 0 on the top of casing I 0, its normal starting position).The printing paper |30 is aorded full exposure for the length of time ittakes the escapement mechanism t0 draw the arm H6 into contact with thepointer |02, and, when said arm and pointer engage each other, the bar30 is automatically forced to the right, causing the arm 88 to draw thelug 82 of lever 80 into engagement with the pawl 64 and thereby stop theoscillation of said pawl and the operation of said escapement mechanism.The cessation of operation of said mechanism is the signal to extinguishthe enlarging lamp, since it is then that the printing paper |30 hasbecome exposed for the proper and novelly determined length of time.

It will ybe seen, therefore, that the device not only renders itpossible to determine the proper time for any exposure in the enlargingprocess, but that `it also serves as a timer during said process, Itrecords the proper exposure on the test strip by automatically shuttingoff said test strip from exposure in an infinite number of progressivephases of infinitesimal duration. The speed of the shutter travel neednot be uniform during the operation of exposing the test strip, sincethis speed, no matter what it is, need only be duplicated during thetiming process. This means that the carefully described escapementmechanism, which furnishes the motive power for driving the shutter, hasbeen selected purely for the purpose of illustrating some means forfurnishing said power, but it should be readily understood that theinvention contemplates its replacement with any other suitable drivingsource, such as an electric motor, a vibrator, or any suitablepneumatic, hydraulic or mechanical driving force the driving motion ofwhich during the testing operation can be duplicated during the timingoperation.

Thetest strip has been described as being stationarily held and theshutter has been described as being drawn longitudinally over the teststrip. However, it is to be understood that the scope of the inventionincludes holding the shutter stationarily and moving the test striprelatively thereto. Also, the shutter may be of any material having asection which permits free passage of light therethrough and anothersection which preventssuch free passage. The shutter and test strip maybe moved relatively to each other in any direction other thanlongitudinally, such as rotatably, by replacing the shutter shown with adisc-shaped shutter having a hole therein through which light may passto expose the test strip thereunder, without departing from the spiritof the invention. It is to be readily understood also that audible orvisible indicating means can be provided for indicating the exact timethe arm IE6 and pointer |02 come into contact, there being no electricalsources or connections shown for and between the elements but it beingcontemplated that the ordinary electrician or mechanic is capable offurnishing same and that same will be so furnished. It is alsocontemplated that the invention can readily be made adaptable forchecking the gamma of the developing solution or developer in thedevelopment of motion picture positives and negatives. Also, theinvention can be made readily adaptable for use in engraving and otherof such fields of endeavor.

Although the invention has been described With some detail it is notintended that such description be definitive of the limits of theinventive idea. The right is reserved to make such changes in thedetails of construction and arrangementJ of parts as will come withinthe purview of the attached claim.

What I claim is:

In a device of the character described, a casing in which a section ofsensitized printing paper is removably supported, an aperture formed ina wall of said casing over the paper, a shutter supported within saidcasing, means confined within said casing and operatively connected tosaid shutter for selectively moving the latter in one direction acrosssaid aperture above the paper, means accessible externally of saidcasing and operatively connected to said shutter to enable the latter tobe moved in the opposite direction, a stop member carried by saidshutter for movement therewith and having a portion extending laterallytherefrom externally of said casing, a support carried within saidcasing, a contact member for said laterally extending por tion andcarried in the path of travel thereof by said support externally of saidcasing, and means operatively interconnecting said support and saidcontact member for retaining the latter in any one of a plurality ofselective positions on said support.

MAURICE L. ASH. JR.

